Optimize position and factor out logic to compute compressed tick i…

…n `TickBitmap` (#654) * Optimize `TickBitmap.position` using assembly * Factor out logic to compute `compressed` to a `compress` function * Add fuzz test for `compress` and `position` * Replace `compressed + 1` by `++compressed` in `nextInitializedTickWithinOneWord`
Uniswap · May 17, 2024 · edc9b10 · edc9b10
1 parent 6786fd4
commit edc9b10
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Showing 33 changed files with 66 additions and 39 deletions.
diff --git a/.forge-snapshots/addLiquidity CA fee.snap b/.forge-snapshots/addLiquidity CA fee.snap
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diff --git a/.forge-snapshots/addLiquidity with empty hook.snap b/.forge-snapshots/addLiquidity with empty hook.snap
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diff --git a/.forge-snapshots/create new liquidity to a position with salt.snap b/.forge-snapshots/create new liquidity to a position with salt.snap
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diff --git a/.forge-snapshots/flipTick_flippingFirstTickInWordToInitialized.snap b/.forge-snapshots/flipTick_flippingFirstTickInWordToInitialized.snap
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diff --git a/.forge-snapshots/flipTick_flippingSecondTickInWordToInitialized.snap b/.forge-snapshots/flipTick_flippingSecondTickInWordToInitialized.snap
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diff --git a/.forge-snapshots/nextInitializedTickWithinOneWord_lteFalse_forEntireWord.snap b/.forge-snapshots/nextInitializedTickWithinOneWord_lteFalse_forEntireWord.snap
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diff --git a/.forge-snapshots/nextInitializedTickWithinOneWord_lteFalse_justBelowBoundary.snap b/.forge-snapshots/nextInitializedTickWithinOneWord_lteFalse_justBelowBoundary.snap
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diff --git a/.forge-snapshots/nextInitializedTickWithinOneWord_lteTrue_forEntireWord.snap b/.forge-snapshots/nextInitializedTickWithinOneWord_lteTrue_forEntireWord.snap
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diff --git a/.forge-snapshots/nextInitializedTickWithinOneWord_lteTrue_justBelowBoundary.snap b/.forge-snapshots/nextInitializedTickWithinOneWord_lteTrue_justBelowBoundary.snap
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diff --git a/.forge-snapshots/nextInitializedTickWithinOneWord_lteTrue_onBoundary_gas.snap b/.forge-snapshots/nextInitializedTickWithinOneWord_lteTrue_onBoundary_gas.snap
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diff --git a/.forge-snapshots/poolManager bytecode size.snap b/.forge-snapshots/poolManager bytecode size.snap
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diff --git a/.forge-snapshots/removeLiquidity CA fee.snap b/.forge-snapshots/removeLiquidity CA fee.snap
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diff --git a/.forge-snapshots/removeLiquidity with empty hook.snap b/.forge-snapshots/removeLiquidity with empty hook.snap
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diff --git a/.forge-snapshots/removeLiquidity with native token.snap b/.forge-snapshots/removeLiquidity with native token.snap
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diff --git a/.forge-snapshots/simple addLiquidity.snap b/.forge-snapshots/simple addLiquidity.snap
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diff --git a/.forge-snapshots/simple removeLiquidity.snap b/.forge-snapshots/simple removeLiquidity.snap
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diff --git a/.forge-snapshots/simple swap with native.snap b/.forge-snapshots/simple swap with native.snap
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diff --git a/.forge-snapshots/simple swap.snap b/.forge-snapshots/simple swap.snap
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diff --git a/.forge-snapshots/swap CA fee on unspecified.snap b/.forge-snapshots/swap CA fee on unspecified.snap
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diff --git a/.forge-snapshots/swap against liquidity with native token.snap b/.forge-snapshots/swap against liquidity with native token.snap
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diff --git a/.forge-snapshots/swap against liquidity.snap b/.forge-snapshots/swap against liquidity.snap
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diff --git a/.forge-snapshots/swap burn 6909 for input.snap b/.forge-snapshots/swap burn 6909 for input.snap
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diff --git a/.forge-snapshots/swap burn native 6909 for input.snap b/.forge-snapshots/swap burn native 6909 for input.snap
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diff --git a/.forge-snapshots/swap mint native output as 6909.snap b/.forge-snapshots/swap mint native output as 6909.snap
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diff --git a/.forge-snapshots/swap mint output as 6909.snap b/.forge-snapshots/swap mint output as 6909.snap
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diff --git a/.forge-snapshots/swap skips hook call if hook is caller.snap b/.forge-snapshots/swap skips hook call if hook is caller.snap
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diff --git a/.forge-snapshots/swap with dynamic fee.snap b/.forge-snapshots/swap with dynamic fee.snap
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diff --git a/.forge-snapshots/swap with hooks.snap b/.forge-snapshots/swap with hooks.snap
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diff --git a/.forge-snapshots/swap with lp fee and protocol fee.snap b/.forge-snapshots/swap with lp fee and protocol fee.snap
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diff --git a/.forge-snapshots/swap with return dynamic fee.snap b/.forge-snapshots/swap with return dynamic fee.snap
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diff --git a/.forge-snapshots/update dynamic fee in before swap.snap b/.forge-snapshots/update dynamic fee in before swap.snap
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diff --git a/src/libraries/TickBitmap.sol b/src/libraries/TickBitmap.sol
@@ -12,14 +12,29 @@ library TickBitmap {
     /// @param tickSpacing The tick spacing of the pool
     error TickMisaligned(int24 tick, int24 tickSpacing);
 
+    /// @dev round towards negative infinity
+    function compress(int24 tick, int24 tickSpacing) internal pure returns (int24 compressed) {
+        // compressed = tick / tickSpacing;
+        // if (tick < 0 && tick % tickSpacing != 0) compressed--;
+        assembly {
+            compressed :=
+                sub(
+                    sdiv(tick, tickSpacing),
+                    // if (tick < 0 && tick % tickSpacing != 0) then tick % tickSpacing < 0, vice versa
+                    slt(smod(tick, tickSpacing), 0)
+                )
+        }
+    }
+
     /// @notice Computes the position in the mapping where the initialized bit for a tick lives
     /// @param tick The tick for which to compute the position
     /// @return wordPos The key in the mapping containing the word in which the bit is stored
     /// @return bitPos The bit position in the word where the flag is stored
     function position(int24 tick) internal pure returns (int16 wordPos, uint8 bitPos) {
-        unchecked {
-            wordPos = int16(tick >> 8);
-            bitPos = uint8(int8(tick & (256 - 1)));
+        assembly {
+            // signed arithmetic shift right
+            wordPos := sar(8, tick)
+            bitPos := and(tick, 0xff)
         }
     }
 
@@ -51,8 +66,7 @@ library TickBitmap {
         bool lte
     ) internal view returns (int24 next, bool initialized) {
         unchecked {
-            int24 compressed = tick / tickSpacing;
-            if (tick < 0 && tick % tickSpacing != 0) compressed--; // round towards negative infinity
+            int24 compressed = compress(tick, tickSpacing);
 
             if (lte) {
                 (int16 wordPos, uint8 bitPos) = position(compressed);
@@ -68,7 +82,7 @@ library TickBitmap {
                     : (compressed - int24(uint24(bitPos))) * tickSpacing;
             } else {
                 // start from the word of the next tick, since the current tick state doesn't matter
-                (int16 wordPos, uint8 bitPos) = position(compressed + 1);
+                (int16 wordPos, uint8 bitPos) = position(++compressed);
                 // all the 1s at or to the left of the bitPos
                 uint256 mask = ~((1 << bitPos) - 1);
                 uint256 masked = self[wordPos] & mask;
@@ -77,8 +91,8 @@ library TickBitmap {
                 initialized = masked != 0;
                 // overflow/underflow is possible, but prevented externally by limiting both tickSpacing and tick
                 next = initialized
-                    ? (compressed + 1 + int24(uint24(BitMath.leastSignificantBit(masked) - bitPos))) * tickSpacing
-                    : (compressed + 1 + int24(uint24(type(uint8).max - bitPos))) * tickSpacing;
+                    ? (compressed + int24(uint24(BitMath.leastSignificantBit(masked) - bitPos))) * tickSpacing
+                    : (compressed + int24(uint24(type(uint8).max - bitPos))) * tickSpacing;
             }
         }
     }

diff --git a/test/libraries/TickBitmap.t.sol b/test/libraries/TickBitmap.t.sol
@@ -23,6 +23,19 @@ contract TickBitmapTest is Test, GasSnapshot {
         }
     }
 
+    function test_fuzz_compress(int24 tick, int24 tickSpacing) public pure {
+        tickSpacing = int24(bound(tickSpacing, 1, type(int24).max));
+        int24 compressed = tick / tickSpacing;
+        if (tick < 0 && tick % tickSpacing != 0) compressed--;
+        assertEq(TickBitmap.compress(tick, tickSpacing), compressed);
+    }
+
+    function test_fuzz_position(int24 tick) public pure {
+        (int16 wordPos, uint8 bitPos) = TickBitmap.position(tick);
+        assertEq(wordPos, tick >> 8);
+        assertEq(bitPos, uint8(int8(tick % 256)));
+    }
+
     function test_isInitialized_isFalseAtFirst() public view {
         assertEq(isInitialized(1), false);
     }